An Improved Determination of the Lithium Depletion Boundary Age of Blanco 1 and a First Look on the Effects of Magnetic Activity

Abstract

The Lithium Depletion Boundary (LDB) is a robust method for accurately determining the ages of young clusters, but most pre-main-sequence models used to derive LDB ages do not include the effects of magnetic activity on stellar properties. In light of this, we present results from our spectroscopic study of the very low-mass members of the southern open cluster Blanco 1 using the Gemini-North telescope, program IDs: GN-2009B-Q-53 and GN-2010B-Q-96. We obtained GMOS spectra at intermediate resolution for cluster candidate members with $I$$\approx$13--20 mag. From our sample of 43 spectra, we find 14 probable cluster members by considering proximity to the cluster sequence in an $I/I-K{}_{\mathrm{s}}$ color-magnitude diagram, agreement with the cluster's systemic radial velocity, and magnetic activity as a youth indicator. We systematically analyze the H$\alpha$ and Li features and update the LDB age of Blanco 1 to be $126_{-14}^{+13}$ Myr. Our new LDB age for Blanco 1 shows remarkable coevality with the benchmark Pleiades open cluster. Using available empirical activity corrections, we investigate the effects of magnetic activity on the LDB age of Blanco 1. Accounting for activity, we infer a corrected LDB age of $114_{-10}^{+9}$ Myr. This work demonstrates the importance of accounting for magnetic activity on LDB inferred stellar ages, suggesting the need to re-investigate previous LDB age determinations.

25 pages, 12 figures, 3 tables

References in corpus (6)

• Low-Mass Dwarf Template Spectra from the Sloan Digital Sky Survey
• The effect of activity on stellar temperatures and radii
• Near and Mid-IR Photometry of the Pleiades, and a New List of Substellar Candidate Members
• A maximum likelihood method for fitting colour-magnitude diagrams
• Model Atmospheres From Very Low Mass Stars to Brown Dwarfs
• The lower mass function of the young open cluster Blanco 1: from 30 Mjup to 3 Mo

Cited by in corpus (9)

• Extended stellar systems in the solar neighborhood -- V. Discovery of coronae of nearby star clusters
• Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster
• Different Fates of Young Star Clusters After Gas Expulsion
• Lithium depletion boundary, stellar associations, and Gaia
• The rotation period distribution of the rich Pleiades-age Southern open cluster NGC 2516. Existence of a representative zero-age main sequence distribution
• A new sample of warm extreme debris disks from the ALLWISE catalog
• NGTS clusters survey -- III: A low-mass eclipsing binary in the Blanco 1 open cluster spanning the fully convective boundary
• Theoretical predictions of surface light element abundances in protostellar and pre-Main Sequence phase
• Search for the sub-stellar lithium depletion boundary in the open star cluster Coma Berenices